1. Field of the Invention
The invention relates to coking industry, and more specifically to coke oven constructions having a horizontal coking chamber confined between two heating walls which comprise vertical heating flues arranged in pairs.
2. Description of the Prior Art
Modern coke ovens with horizontal coking chambers confined between heating walls which comprise vertical heating flues arranged in pairs are known to find ever increasing use in industry. Every pair of vertical flues is separated from the next pair by a blind partition. In turn, every pair of vertical flues is provided with a separating partition formed with a flow port at the top. The flow port is intended for passing combustion products from one vertical flue to the other. The separating partition is also provided with a recirculation orifice in the bottom portion.
In operation, gas and air are supplied to one vertical flue of every pair. Thus, combustion occurs simultaneously within half of the wall heating flues. Combustion products pass through the flow port from one flue into the other, i.e. adjoining vertical flue, flow downwards and out of the flue on the way to a checker chamber. A portion of combustion products returns through the recirculation orific into the vertical heating flue in which combustion takes place. Gas flow in the adjoining vertical heating flues periodically changes direction, i.e. combustion takes place alternately in one or the other flue, and accordingly combustion products are removed through the adjoining flue, a predetermined amount of combustion products being constantly passed through the flow port in one or the other direction.
Heat resulting from combustion is transferred to the oven coking chamber where coal charge is transformed into coke without air access.
In the process of coking coal charge shrinks. Depending on the granulometric and component composition of the coal charge and on coal resources base the coal charge shrinkage value varies. According to an anticipated coal charge shrinkage value the requisite heating level is selected for a specific coke oven battery, i.e. the distance between the coking chamber top and the flow port top. However, the resource base and coal are sometimes changed, and accordingly, the charge shrinkage value is changed which, with a constant heating level in a particular coke oven battery, causes under or overheating of the coke upper portion. This results in a deteriorated coke oven operating conditions and coke quality and in lower production rates.
Various procedures are resorted to in order to obviate the above shortcoming. Thus, when the coal charge shrinks beyond the rated heating level, the upper portion of the charge is additionally compressed with a planing rod, or the height of the space under the coking chamber roof is decreased by filling the chamber with excess coal charge, or the burners positioned in the heating wall vertical flues are lowered, or graphite deposits, on the coking chamber walls and roof are burned (with the oven empty), or an anarbitrary combination of the foregoing procedures is used, etc. All the above procedures are directed to the elimination of overheating of the coke cake upper portion and decreasing the temperature in the upper portion of the coking chamber.
If the coal charge shrinkage value is less than the rated one, the amount of coal charge in the coking chamber is decreased, or the duration of coking is increased, or both these procedures are used simultaneously.
However, the aforesaid measures are insufficiently effective and require extra operational costs.
To obviate the overheating or underheating of the coal charge, there have been attempts to provide a possibility of adjusting the heating level in a coke oven by improving the construction of heating walls.
Thus, known in the art is a coke oven with a horizontal coking chamber confined between heating walls which comprise vertical heating flues arranged in pairs, as disclosed in the German Pat. No. 677101 Nat. Class 10a/6. According to said Patent the upper portion of a partition separating adjoining vertical heating flues is formed with a flow port having a fixed bottom edge.
The cover of the vertical heating flues and the top portion of the separating partition forming the top edge of the flow port are detachable. The level of heating in the coke oven is to be adjusted by lowering the port top edge. To accomplish this a short upper portion of the partition is substituted by a longer one, and an additional cover is inserted.
Theoretically, the foregoing oven may be constructed and used, but the commercial manufacture thereof presents certain difficulties arising from the need to disassemble the heating wall cover which envolves objectionably high capital cost. In addition, the major amount of combustion products flows through the lower portion of the flow port. Consequently, an adjustment of the port top edge position effects but insignifically the heating of the upper portion of the vertical heating flues. It should be noted that a change, e.g. a decrease in the flow port clear opening results in an increased hydraulic resistance of the port which disturbs hydraulic conditions of the coke oven heating system.
Disclosed in the Germany Pat. No. 1,671,325 and the Japan Pat. No. 46-20146 is a horizontal chamber coke oven which comprises a horizontal coking chamber confined between heating walls with vertical heating flues arranged in pairs. The upper portion of a partition separating adjoining vertical heating flues is formed with a main flow port and an additional one disposed higher with respect to the main flow port. Between said ports a crosspiece of the vertical heating flues is positioned. The crosspiece is formed with an additional flue which is an extension of one of the vertical heating flues but has a lesser clear opening as compared to that of the main flow. The upper portion of the additional flue is provided with a gate for closing this flue at intervals.
According to the above invention the heating level of a coke oven is adjusted by passing some portion of combustion products through the additional flue and flow port from one vertical heating flue to the other. However, the major volume of combustion products takes the shortest course, i.e. flows through the main flow port. Therefore only a negligible quantity of combustion products may pass through the additional flow port, which cannot substantially help in adjusting the temperature in the upper portion of heating flues and hence, in controlling the coke cake heating. Besides, the crosspiece in the upper portion of vertical heating flues creates a hydraulic resistance and decreases heat transfer from the upper portion of the vertical heating flue walls to the coal charge.
Another prior art coke oven comprising a horizontal coking chamber confined between heating walls having vertical heating flues arranged in pairs is disclosed in the German Pat. No. 1671319, in the U.S. Pat. No. 3,519,541, and in the Japan Pat. No. 46-23496. The upper portion of a partition separating adjoining vertical heating flues is provided with two flow ports arranged one above the other. The walls of the vertical heating flues are formed with rectangular pockets in the port location areas, slide gates being mounted on the shoulders of said pockets for reciprocating motion to close alternately one or the other flow port.
The level of heating in the foregoing coke oven is adjusted as follows. When the lower flow port is closed and the upper one is open, combustion products flow from one vertical flue to the other through the upper port and vice versa when the position of the slide gates is reversed. By changing the position of the slide gates it is possible to control the temperature within the upper portion of the vertical heating flues and, accordingly, the temperature in the coking chamber upper portion. The provision of rectangular pockets with the slide gates within the vertical heating flues leads, however, to a considerably increased hydraulic resistance to gas flow. In addition heat transfer to the coking chamber decreases in the area where the slide gates abut upon the walls of the vertical heating flues. It is to be noted that two flow ports having a requisite clear opening occupy a substantial portion of the vertical extent of the partition separating adjoining vertical flues which practically rules out any possibility to control the heating, for shrinkage of different coal charges varies within a considerably narrower range.
Another prior art heating wall of a coke oven with a horizontal coking chamber comprises vertical heating flues arranged in pairs, every pair being separated by a partition formed in its upper portion with a flow port which is provided with slotlike guides for mounting an extensible slide gate incorporating means for introducing the hook of a rod and displacing the slide gate.
The slot-like guides are horizontally mounted on shoulders adjoining the upper and the lower edges, respectively, of the flow port and projecting inwardly within the vertical heating flue. Another flow port is formed in the partition above the aforesaid flow port. A projection extends horizontally along the entire inner diameter of the vertical heating flue between the flow ports and forms a horizontal aperture. This projection serves as a guide and horizontally mounts an extensible slide gate (the USSR Inventor's Certificate No. 57767) Int. Class Cl0v 5/02.
The temperature within the upper portion of the coking chamber is adjusted as follows. If the temperature in the upper portion of the coking chamber is to be raised, combustion products are passed from one vertical heating flue into the other through the upper flow port. In so doing, the lower flow port is closed by the extensible slide gate, the horizontal aperture formed by the horizontally extending projection is open, and vice versa.
Extensible slide gates are more light-weight as compared to non-extensible ones, which makes them easier to move and therefore facilitates the temperature control within the upper portion of the coking chamber. However, the foregoing heating wall is characterized by certain short-comings, some of them being identical to those of prior art coke ovens with heating walls in which the flow port clear opening is closed by slide gates whereas some other being intrinstic in the construction of the heating wall being described.
Thus, the shoulders and projection inside the vertical heating flue substantially increase the hydraulic resistance to the combustion products flow and decrease the active surface of heat transfer from the walls to the coal charge. It is common knowledge, however, that the vertical heating flue must have an unobstructed cross-section and a minimum hydraulic resistance along the full vertical extent, i.e. the flue walls should have no swellings or projections with refractory members positioned thereon. Besides, as the upper or lower flow port is opened to provide for combustion products flow at an appropriate level, the slide gates are driven towards the walls of the vertical heating flues, so that they cover a portion of the wall surface, which results in deterioration of heat transfer into the coking chamber in this area.
It is an object of the invention to provide a coke oven heating wall which allows for temperature to be changed in the upper portion of the coke chamber according to changes in coal charge shrinkage.
Another object of the invention is to provide a heating wall having a flow port in a partition separating adjoining vertical flues arranged in pairs of such a design which allows the vertical position of the flow port to be changed without changing the clear opening area of the flow part or the clear opening of the vertical heating flues along their full vertical extent.
A further object of the invention is to provide a coke oven heating wall which affords temperature control in the upper portion of the coking chamber, necessary for the appropriate heating of the coke cake upper portion in order to improve the coke quality.